This invention relates generally to a moisture analyzing system and, more particularly to a non-contacting radio frequency system for making continuous on-line moisture measurements.
Various types of moisture analyzing systems apply a high frequency electric field to a material under test. While the electric field is being applied, changes in some electrical characteristic are detected and measured to determine moisture content of the material. Included in such systems are those which measure changes in capacitance. Examples of capacitive measuring systems are disclosed in U.S. Pat. Nos. 3,793,595 and 4,259,632. Other systems measure electromagnetic or microwave energy loss within the material. Examples of energy loss measuring systems are disclosed in U.S. Pat. Nos. 3,981,082 and 4,193,027. Still other systems measure frequency change in the applied field, An example of a frequency change measurement system is disclosed in U.S. Pat. No. 3,684,952.
Although providing measurements indicative of moisture content, the above noted prior systems suffer from a number of individual and collective deficiencies. Typical disadvantages of conventional moisture measurement systems are excessive cost, inability to perform on-line measurements, limited accuracy, ambient temperature sensitivity, sensitivity to product density and shape, inability to function in harsh environments, etc.
The object of this invention, therefore, is to provide an improved moisture analyzing system that will alleviate problems associated with prior alternating electric field measurement systems.